How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Amedee Your Own Question

Amedee
Amedee, ASE Master Tech
Category: Car
Satisfied Customers: 21869
Experience:  ASE Master Tech advanced level specialist. Wisconsin certified emissions state inspector
279429
Type Your Car Question Here...
Amedee is online now
A new question is answered every 9 seconds

1987 porsche 924: coil still not firing

Resolved Question:

1987 porsche 924 will not start .getting no fire to plugs.changed coil still not firing.
Submitted: 7 years ago.
Category: Car
Expert:  Amedee replied 7 years ago.
Greetings! With the key on, make sure there is full battery voltage at the coil and with a test light, check to see if there is a ground signal trigger when cranking. THis is the signal at the coil that starts the spark process from the coil.
Customer: replied 7 years ago.
how do I check to see if there is a ground signal trigger?
Customer: replied 7 years ago.
How do I check to see if there is a ground trigger signal?
Expert:  Amedee replied 7 years ago.
Take the alligator clip of the test light and clip it on battery positive. Take the tip of the test light and touch the other wire on the coil (not the power wire) and crank the engine over. THe test light should blink.
Customer: replied 7 years ago.
Test light does not blink @ negative side of coil while cranking.
Customer: replied 7 years ago.
Test light does not blink @ neg. side of coil while cranking.
Expert:  Amedee replied 7 years ago.

This means the computer is not seeing a crank signal.

924 & 944 Models

  1. Turn ignition Off, then remove DME ECU multiple wiring connector.
  2. Connect suitable oscilloscope to terminals 25 and 26 of ECU connector.
  3. Start engine, then observe oscilloscope tube. A single sine wave should be displayed. The oscillation should begin with a positive slope displaying at least 2 volts with a starter speed of at least 200 RPM. As engine speed increases, the display amplitude should also increase.
  4. If transmitter output is less than 2 volts, check clearance between reference mark transmitter and ring gear. Refer to System Service for procedure.
  5. If display shows no transmitter signal, proceed to step 6.
  6. Using suitable ohmmeter, measure between ECU connector terminals 25 and 26 to determine reference mark transmitter coil resistance. Resistance should be .6 - 1600 ohms.
  7. If resistance is not within specifications, replace transmitter.
Customer: replied 7 years ago.
where is ecu located on car
Customer: replied 7 years ago.
where is ecu located on car
Customer: replied 7 years ago.
where is ecu located
Expert:  Amedee replied 7 years ago.

Location
- Passenger footwell
- Under drivers seat [Carrera]

Customer: replied 7 years ago.
checked between 25 and 26 on plug on ecu this circuit is open
Expert:  Amedee replied 7 years ago.

924 & 944 Models

  1. Turn ignition Off, then remove DME ECU multiple wiring connector.
  2. Connect suitable oscilloscope to terminals 8 and 27 of ECU connector.
  3. Turn engine over with starter while observing oscilloscope tube. Sine waves should be displayed with amplitude of 2.5 volts or more from peak to peak.
  4. If amplitude is less than 2.5 volts peak to peak, check clearance between speed sensor and ring gear. Refer to System Service for procedure.
  5. If clearance between ring gear and speed sensor is satisfactory, or if pattern is not displayed or weak, proceed as follows:
    1. Using suitable ohmmeter, measure between ECU connector terminals 8 and 27 to determine speed sensor coil resistance. Resistance should be .6 - 1600 ohms.
    2. Using ohmmeter, measure between ECU connector terminals 5 and 8 to determine speed sensor insulation resistance. Resistance should be 1 M-ohm.
    3. If resistances are not within specifications, replace sensor.

Magnetic Coil Sensors

graphic

Customer: replied 7 years ago.
is this the referance mark or speed mark sensor and where are they located.thank you.........
Expert:  Amedee replied 7 years ago.

Sorry... my references do not tell me where they are located.

If my answer is not good enough, just let me know and I will leave this question open for other experts.

Thanks!

Customer: replied 7 years ago.
that would be great. I have looked on the engine front and back and have not seen a sensor for the crank.thanks.....
Expert:  Amedee replied 7 years ago.
You got it!
Amedee, ASE Master Tech
Category: Car
Satisfied Customers: 21869
Experience: ASE Master Tech advanced level specialist. Wisconsin certified emissions state inspector
Amedee and 15 other Car Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
< Last | Next >
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
  • Excellent reply, and also very quick. Really sounds like the Expert knows what he is talking about. I will be back to use your service when I need more help with my RV. Dutch USA
 
 
 

Meet The Experts:

 
 
 
  • Chris (aka-Moose)

    Technician

    Satisfied Customers:

    846
    16 years of experience
< Last | Next >
  • http://ww2.justanswer.com/uploads/MU/muddyford/2012-6-13_1204_1.64x64.png Chris (aka-Moose)'s Avatar

    Chris (aka-Moose)

    Technician

    Satisfied Customers:

    846
    16 years of experience
  • http://ww2.justanswer.com/uploads/TE/TedG/2012-6-15_14759_avaLarge.64x64.jpg Ted G.'s Avatar

    Ted G.

    ASE Certified Technician

    Satisfied Customers:

    1596
    20 years auto repair experience, ASE Master Tech, Mechanical Failure consultant, Expert Witness
  • http://ww2.justanswer.com/uploads/joecamel90/2008-11-13_03615_head_shot.jpg George H.'s Avatar

    George H.

    ASE Certified Technician

    Satisfied Customers:

    1311
    ASE Master Tech 15+ yrs, AAS Automotive Technology, Factory trained Asian specialist
  • http://ww2.justanswer.com/uploads/AM/amedee/2013-10-24_23656_Amedee1.64x64.jpg Amedee's Avatar

    Amedee

    ASE Master Tech

    Satisfied Customers:

    2367
    ASE Master Tech advanced level specialist
  • http://ww2.justanswer.com/uploads/SU/supermechanic/2013-8-23_03546_500.64x64.jpg Jerry's Avatar

    Jerry

    Master Mechanic

    Satisfied Customers:

    1906
    ASE master, 30+ years. All makes and models. Trouble shooter, shop forman, service manager
  • http://ww2.justanswer.com/uploads/CR/crzydrvr00/2013-11-3_12123_246347.64x64.jpg Richard's Avatar

    Richard

    ASE Certified Technician

    Satisfied Customers:

    942
    12 years Ford Lincoln/Mercury Jaguar dealership as a technician and shop foreman reparing all makes
  • http://ww2.justanswer.com/uploads/ST/Steve7654/2012-6-5_215929_japic800x660.64x64.jpg Steve's Avatar

    Steve

    Auto Service Technician

    Satisfied Customers:

    1980
    25+ yrs experience as a professional working technician; ASE L1 master technician